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34
Selecting apertures and power level in
manual ash
e following tables show the values when ISO 100 is used without the wide
panel or diuser. For other ISO speeds, or if you use the wide panel or diuser,
adjust the aperture settings according to the table on page 38. When using the
twin ash units, the data assumes that the power lever is the same for both units.
If they are set at dierent power levels, see page 37.
e ap
erture values given in the tables are calculated values. e actual lens will
have its own usable aperture range.
Example: Using a 50mm F2.8 M
acro lens when ISO 100, with a pair
of twin ash units with no arm, power level of 1/1, and a
magnication ratio of 1:1
e aperture is calculated at f/90 (refer to the following table).
Ho
wever, the smallest actual aperture possible with this lens is
f/32.
erefore, if you set the power level to 1/1, the picture will be
overexposed.
But if you set the power level to 1/8, you will get a correct
exposure at f/32.
ese following tables show the apertures where the proper exposure of the
illuminated area is obtained. Actual exposure varies according to the subject’s
shape or position (p. 53). Test photographs or bracketing is recommended
especially when the subject is illuminated from side or behind.
e fo
llowing tables show data for certain lenses and magnication ratios. For
other lenses and magnication ratios, see page 55.
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